GoldRush Sourdough Bread Mix.- Non-dairy, easy to mix, no artificial flavors or preservatives. Just add water or beer. It does not get more sour than this! The sourdough culture from San Francisco has become world famous. There is, however, an infinite variety of different sourdough cultures. No two cultures are exactly the same. With the development of instant sourdough mixes, Goldrush has made it possible for you to have natural distinctive flavored sourdough products in a more convenient form. Goldrush bread mix includes instruction for use with bread machines. 20 oz box.